1. Field of the Invention
The present invention relates to a navigation system, and in particular, to a navigation system equipped with portable sub-navigation unit capable of still providing a route guide to a person who carries the sub-navigation unit.
2. Description of Related Art
In recent years, a navigation system for guiding a vehicle has widely used, where a display unit such as a liquid crystal display panel is mounted on the vehicle to display maps. One type of recent navigation systems, which has been eagerly researched for practical use, is a communicating navigation system. In this navigation system, there are provided an information server and on-vehicle navigation terminals. The information server has a database in which pieces of information about maps are stored. Pieces of map information are delivered to each on-vehicle navigation terminal by making use of mobile communication lines. Each on-vehicle terminal detects vehicle data (mobile data), such as vehicle""s own position data, and provides crew members with pieces of information in relation to the navigation.
Meanwhile, portable terminals including a cellular phones and a PDA (personal digital assistance) have been in wide use.
In cases where the foregoing on-vehicle navigation terminal is used to simply guide the vehicle to a destination, the terminal is able to achieve the goal without any problems. However, such terminal encounters a problem, if facilities to be targeted are located far from a parking lot. The problem tends to be more frequent in inner-city districts or pleasure facilities. In such a case, the vehicle should be parked at the parking lot, and persons are obliged to go to the facilities (a final destination) on foot. Walking from the parking lot to the facilities may make persons worry about a further route guide to the facilities. There is even a fear that persons may be lost, if the route is complicated or in ordered good conditions.
The present invention has been made in view of the above circumstances, and an object of the present invention is, therefore, to provide a navigation system capable of, in addition to a route guide to a vehicle""s stop position apart from a final destination, guiding a route from the vehicle""s stop position to the final destination to a person in a steady manner, even when the vehicle""s stop position is fairly distinct from the final destination.
In order to realize the above object, the present invention provides a navigation system having a first route search processing unit and a second route search processing unit. The first route search processing unit is configured to perform a first route search to produce map information to guide a first movable member carrying a navigation apparatus from a current position to a destination and to produce first-movable-member map information formed by laying route information on the map information. Meanwhile the second route search processing unit is configured to perform a second route search to produce further map information to guide a second movable member carrying a portable sub-navigation unit from a further current position to the destination and to produce second-movable-member map information formed by laying further route information on the further map information. The further current position is an instantaneous position at which the second route search is performed.
Accordingly, a route guide on the first-movable-member map information is provided from an initial current position toward a destination. In cases where the first movable member (for example, a vehicle) reaches a certain position (for example, a parking lot) but there is still a remaining route to the destination, a guide for the remaining route is continued by the use of the second-movable-member map information. In cases where the certain position is distant from the destination, a person is obliged to walk from the certain position to the destination. In such a case, the portable sub-navigation unit is able to steadily guide, to the person, the route between the certain position and the destination, with the possibility of losing person""s way almost completely eliminated.
Preferably, the portable sub-navigation unit carried by the second movable member is a portable information device wire-less communicable with the navigation apparatus and the navigation system further comprises a transfer unit configured to transfer the second-movable-member map information to the portable information device. Thus, it is possible to display the second-movable-member map information on the portable information device.
Still preferably, the first movable member is a vehicle having an engine and the second route search processing unit is configured to automatically start the second route search in response to a turn-off operation of the engine of the vehicle. Hence, after a route guide obtained on the vehicle, a route guide by the portable information device is automatically started and continued.
It is preferred that the second route search processing unit is configured to produce the second-movable-member map information consisting of a plurality of maps formed depending on distances from the destination. In consequence, an easy-to-understand map information is given the person who walks toward the destination after getting off the vehicle.
It is also preferred that at least one of the plurality of maps solely includes both of the further current position and the destination in cases where each of the maps is displayed on a screen of the portable information device. The destination is displayed on the portable information device together with the further current position (i.e., a parking lot), thus providing overviewed map information to the person who carries the device.
By way of example, the plurality of maps are formed based on the same scale. It is therefore possible to give easy-to-observe maps to the person who carries the portable information device.
It is also preferred that the plurality of maps are formed into enlarged maps showing a predetermined region in which a route including a right-and-left-turn crossing is placed with the crossing located at a center of the region, the route being selected from routes searched by the second route search processing unit. Thus, easy-to-observe maps are provided to the person who carries the portable information device.
Further, preferably, the second route search processing unit is configured to produce each of the plurality of maps so as to show a travel direction of the second movable member upward on a display screen of the portable information device. Maps are thus easier for the person to view.
Still further, it is preferred that the second route search processing unit is configured to produce each of the plurality of maps so as to display on each map information about a transit time to be expected, in cases where the second movable member travels along a route guided by the second route search processing unit. Thus, easy-to-observe maps are provided to the person who carries the portable information device.
It is also preferred that the second route search processing unit is configured to additionally perform search a route from the destination to the further current position. Therefore, even when the person who carries the portable information device returns from the destination to, for example, a parking lot at which a person""s vehicle is parked (i.e., the further current position), a route guide is surely provided to the person who carries the device.
According to the present invention, as other aspects, a navigation method, a program for navigation, and an information recording medium for navigation are provided. As a result, the same or identical operations and advantages as or to the above primary ones can be provided.